M3: Dr Smith, while we’re waiting for the next patient to come in, I wonder if I could ask you about the last two patients? I’m confused about aspirin.
Dr S: Who isn’t? [smiles] Go ahead.
M3: Both had diabetes and hypertension. Neither one has had a stroke. Similar ages. One is taking aspirin, and the other isn’t.
Dr S: You are paying attention and trying to draw rules out of what we’re doing. That’s great. There won’t be just one study that we can rely upon. We’ll have to use an organization’s guidelines to help with this kind of a decision that pulls together all the research and makes a judgement call. Which organization’s recommendations do you like the best? Which guideline should we use?
M3: Well, on family medicine, I think most of my teachers like the United States Preventive Services Task Force (USPSTF). But, for diabetes, I hear most people refer to the American Diabetes Association (ADA).
Dr S: OK. But they don’t agree completely, do they? What does the ADA say?
M3: They said recently that patients under a certain age should NOT be on low dose aspirin.
Dr S: Right. Women less than 60 and men less than 50 with less than 10% risk of a cardiovascular event within 10 years should not be on aspirin. Wouldn’t it be great to use a calculator on a Web site—to calculate that 10% risk, for example?
M3: Yes! Show me.
Dr S: Ha. Caught you. There are a number of calculators, and the ADA does not recommend a specific one to use to calculate risk, not even its own calculator.
- The ARIC CHD Risk Calculator
- The UKPDS Risk Engine
- The Diabetes PHD (Personal Health Decisions) from the ADA
- Heart to Heart
I had these calculators bookmarked because Dr Seawright and I presented a comparison of them recently at the STFM Annual Spring Conference. What do you think?
M3: The PHD one requires more than one screen of data entry, and you have to enter in medications. That process seems cumbersome.
Dr S: I agree. Why do you think different calculators ask for different information?
M3: I guess that they are based on different research studies?
Dr S: Exactly. So—maybe—which one would you use if the patient had an enlarged heart?
M3: I’d use the Med Decisions one, because it’s probably based on patients with and without enlarged hearts. It’s the only calculator that asks for that data.
Dr S: Right. And the UKPDS calculator would be good if the patient has atrial fibrillation or was of Caribbean heritage. Let’s take an example of a patient and see what the calculators say about the risk. The last patient.
M3: OK. 52 years old, African American woman. Systolic blood pressure is 142 mm Hg, total cholesterol is 150 mg/dL, HDL is 35. She doesn’t smoke, never did. She has diabetes for how long?
Dr S: 16 years.
M3: Last hemoglobin A1c was 8.5%. Does she have a large heart?
Dr S: Let me help. She does have an enlarged heart but not atrial fibrillation. She is taking chlorthalidone 25 mg a day for high blood pressure.
M3: The Med-Decisions calculator says that the 10-year risk of heart disease is 28%. UKPDS says 4%. And the ARIC risk calculator says 7%. So, the risk is somewhere between 4% and 28%?
Dr S: Not as helpful as we hoped, was it? What’s the bottom line?
M3: I can’t rely upon just one calculator.
Dr S: I agree. It makes sense to use the calculator that’s based on patients who look most like your patient. But that isn’t always possible. And use the risk calculation results with caution. We have a third patient in the room now, and she has diabetes too. Let’s see what you recommend this time, in terms of aspirin.
Laura Lee Smith, MD, and Katherine Seawright, MD, Trident/MUSC Family Medicine Residency Program, North Charleston, SC, Authors
Alec Chessman, MD, Medical University of South Carolina, Editor
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